Abstract

Background

Claudin-6 is a candidate tumor suppressor gene in breast cancer, and has been shown
to be regulated by DNA methylation and histone modification in breast cancer lines.
However, the expression of claudin-6 in breast invasive ductal carcinomas and correlation
with clinical behavior or expression of other markers is unclear. We considered that
the expression pattern of claudin-6 might be related to the expression of DNA methylation
associated proteins (methyl-CpG binding protein 2 (MeCP2) and DNA methyltransferase
1 (DNMT1)) and histone modification associated proteins (histone deacetylase 1 (HDAC1),
acetyl-histone H3 (H3Ac) and acetyl- histone H4 (H4Ac)).

Conclusions

Our results show that claudin-6 protein is significantly down-regulated in breast
invasive ductal carcinomas and is an important correlate with lymphatic metastasis,
but claudin-6 down-regulation was not correlated with upregulation of the methylation
associated proteins (MeCP2, DNMT1) or histone modification associated proteins (HDAC1,
H3Ac, H4Ac). Interestingly, the expression of MeCP2 was positively correlated with
the expression of H3Ac and H3Ac protein expression was positively correlated with
the expression of H4Ac in breast invasive ductal carcinoma